In the conventional two roll sugarcane crushing mill a plurality of two roll mill modules are used in tandem. Each of the two roll mill module comprises a bottom roll and top roll mounted in a pair of closed frame/headstock provided at the two ends, for allowing the cane/bagasse feeding between the two rolls, these rolls are kept inclined, instead of vertical, that is the central axis of top and bottom rolls is inclined at about 25 degree from the vertical axis. The top roll is directly loaded to press the same towards the bottom roll. For this top roll bearings slide in the headstock/frame at the two ends of the top roll.
Sometimes, a feeder roller which is generally a grooved roller fixedly mounted on the frame, without any scraper-cum-deflector, is provided to compress/compact the prepared cane/bagasse mat for feeding between the two rolls.
When two or more feeder rollers are used for compressing/compacting the cane/bagasse mat to be into the gap between the two rolls, a stationary closed pressure chute is also required to be provided between the feeder rollers and main crushing rolls.
The main draw backs of the conventional two roll sugarcane crushing mill are as given below:
i) The top and bottom rolls being mounted in the inclined position, top roll bearings slide in the inclined plane resulting in side friction on the bearings and more functional load and more maintenance.
ii) The top roll is directly loaded to press it against the bottom roll for which top roll bearings slide in the head stock at the two ends, and are subjected to uneven wear at top and bottom sides, resulting into sluggish floating of the top roll instead of free floating.
iii) The top roll being directly loaded and central axis of top and bottom rolls being inclined more hydraulic load is required needing more power consumption for a desired load.
iv) Hydraulic cylinder being rigidly mounted in an inclined plane for direct loading of top roll, hydraulic seal failure is considerably more.
v) In case of a single feeder roller provided for compact feeding of cane/bagasse the compressed cane is again expanded, as there is no scraper/deflector provided with the feeder roller, thereby gripping angle of the main crushing rolls is increased resulting into reduced cane crushing capacity of the mill, and higher power consumption due to more number of rolls.
vi) As there is no scraper or any other juice removing means like lotus type construction provided with the feeder roller, juice is not removed by the feeder roller, resulting into lower juice extraction efficiency/capacity of the mill and more power consumption as more number of rolls will be required for the same juice extraction capacity of the mill.
vii) As the top and bottom rolls are mounted in a pair of closed frames and are directly loaded, while dismantling the rolls for maintenance and/or repairing the top cap with hydraulic loading means is also to be removed and then only the top and bottom rolls are lifted upwards, which takes more time and labor, thus besides higher maintenance cost, mill down time is also more, resulting in lower productivity of the crushing mill.
viii) In case of two or more feeder rollers needing a stationary closed pressure chute provided between the feeder rollers and the main crushing rolls, all the inherent drawbacks of the stationary closed pressure chute, which are well known and described in the present inventor's co-pending patent application Indian Patent application No. 32/130M/93, are there, resulting in higher initial cost and maintenance cost, more mill down time, more power requirement and lower productivity of the mill.